The causes analysis on over-temperature of main steam of supercritical once-through boiler at initial stage of start-up

At the start-up process during commissioning period of No.1 600 MW supercritical units in Anhui Huadian Suzhou Power Generation Corporation Limited,the problem of little over-temperature of the main steam occurred many times,especially in the first time of parallel in power grid.The main reasons were the small burning heat load,too much air flow and fuel,larger feedwater flow,unreasonable designs of attemperating water.In these regard,the series of measures were adopted,such as lowering the feedwater quantity during ignition,reducing fuel input,improving combustion,increasing combustion heat load,controlling the negative pressure of furnace at-100 Pa,the total air flow of 0.5 ~ 0.6 million m3/h,and raising feedwater temperature above 100℃,etc.the problem of over-temperature of main steam during initial stage of start-up process has been solved,and all the parameters have reached designed demands.